Molecular pathway and cell state responsible for dissociation-induced apoptosis in human pluripotent stem cells

Human embryonic stem cells (hESCs), unlike mouse ones (mESCs), are vulnerable to apoptosis upon dissociation. Here, we show that the apoptosis, which is of a nonanoikis type, is caused by ROCK-dependent hyperactivation of actomyosin and efficiently suppressed by the myosin inhibitor Blebbistatin. The actomyosin hyperactivation is triggered by the loss of E-cadherin-dependent intercellular contact and also observed in dissociated mouse epiblast-derived pluripotent cells but not in mESCs. We reveal that Abr, a unique Rho-GEF family factor containing a functional Rac-GAP domain, is an indispensable upstream regulator of the apoptosis and ROCK/myosin hyperactivation. Rho activation coupled with Rac inhibition is induced in hESCs upon dissociation, but not in Abr-depleted hESCs or mESCs. Furthermore, artificial Rho or ROCK activation with Rac inhibition restores the vulnerability of Abr-depleted hESCs to dissociation-induced apoptosis. Thus, the Abr-dependent "Rho-high/Rac-low" state plays a decisive role in initiating the dissociation-induced actomyosin hyperactivation and apoptosis in hESCs.

Rho and anillin-dependent control of mDia2 localization and function in cytokinesis

Diaphanous-related formin, mDia, is an actin nucleation/polymerization factor functioning downstream of the small GTPase Rho. We found that, in addition to the Rho GTPase-mediated activation, the interaction between mDia2 and anillin is required for the localization and function of mDia2 in cytokinesis.

Diaphanous-related formin, mDia, is an actin nucleation/polymerization factor functioning downstream of the small GTPase Rho. Although Rho is critically involved in cytokinesis, it remains elusive how Rho effectors and other regulators of cytoskeletons work together to accomplish this process. Here we focused on mDia2, an mDia isoform involved in cytokinesis of NIH 3T3 cells, and analyzed mechanisms of its localization in cytokinesis. We found that targeting of mDia2 to the cleavage furrow requires not only its binding to RhoA but also its diaphanous-inhibitory domain (DID). We then performed pulldown assays using a fragment containing the latter domain as a bait and identified anillin as a novel mDia2 interaction partner. The anillin-binding is competitive with the diaphanous autoregulatory domain (DAD) of mDia2 in its autoinhibitory interaction. A series of RNA interference and functional rescue experiments has revealed that, in addition to the Rho GTPase-mediated activation, the interaction between mDia2 and anillin is required for the localization and function of mDia2 in cytokinesis.

Rho signaling, ROCK and mDia1, in transformation, metastasis and invasion

The Rho subgroup of the Rho GTPases consisting of RhoA, RhoB and RhoC induces a specific type of actin cytoskeleton and carry out a variety of functions in the cell. mDia and ROCK are downstream effectors of Rho mediating Rho action on the actin cytoskeleton; mDia produces actin filaments by nucleation and polymerization and ROCK activate myosin to cross-link them for induction of actomyosin bundles and contractility. mDia is potentially linked to Rac activation and membrane ruffle formation through c-Src-induced phosphorylation of focal adhesion proteins, and ROCK antagonizes this mDia action. Thus, cell morphogenesis, adhesion, and motility can be determined by the balance between mDia and ROCK activities. Though they are not oncogenes by themselves, overexpression of RhoA and RhoC are often found in clinical cancers, and RhoC has been repeatedly identified as a gene associated with metastasis. The Rho-ROCK pathway is implicated in Ras-mediated transformation, the amoeboid movement of tumor cells in the three-dimensional matrix, and transmigration of tumor cells through the mesothelial monolayer. On the other hand, the Rho-mDia1 pathway is implicated in Src-mediated remodeling of focal adhesions and migration of tumor cells. There is also an indication that the Rho pathway other than ROCK is involved in Src-mediated induction of podosome and regulation of matrix metalloproteases. Thus, Rho mediates various phenotypes of malignant transformation by Ras and Src through its effectors, ROCK and mDia.

mDia2 shuttles between the nucleus and the cytoplasm through the importin-{alpha}/{beta}- and CRM1-mediated nuclear transport mechanism

Mammalian homolog of Drosophila diaphanous (mDia) consisting of three isoforms, mDia1, mDia2, and mDia3, is an effector of Rho GTPases that catalyzes actin nucleation and polymerization. Although the mDia actions on actin dynamics in the cytoplasm have been well studied, whether mDia accumulates and functions in the nucleus remains largely unknown. Given the presence of actin and actin-associated proteins in the nucleus, we have examined nuclear localization of mDia isoforms. We expressed each of mDia isoforms as a green fluorescent protein fusion protein and examined their localization. Although all the mDia isoforms were localized predominantly in the cytoplasm under the steady-state conditions, mDia2 and not mDia1 or mDia3 accumulated extensively in the nucleus upon treatment with leptomycin B (LMB), an inhibitor of CRM1-dependent nuclear export. The LMB-induced nuclear accumulation was confirmed for endogenous mDia2 by using an antibody specific to mDia2. Studies using green fluorescent protein fusions of various truncation mDia2 mutants and point mutants of some of these proteins identified a functional nuclear localization signal in the N terminus of mDia2 and at least one functional nuclear export signal in the C terminus. The nuclear localization signal of mDia2 bound to importin-alpha and was imported into the nucleus by importin-alpha/beta complex in an in vitro transport assay. Consistently, depletion of importin-beta with RNA interference suppressed the LMB-induced nuclear localization of endogenous mDia2. These results suggest that mDia2 continuously shuttles between the nucleus and the cytoplasm using specific nuclear transport machinery composing of importin-alpha/beta and CRM1.

Persistent diffuse pulmonary interstitial emphysema mimicking pulmonary emphysema

A 69-year-old male non-smoker with a history of atopic asthma presented with symptoms suggestive of chronic obstructive pulmonary disease and this appeared to be corroborated by lung function testing and a chest radiograph. However, a chest CT showed no evidence of pulmonary emphysema and instead demonstrated free air along the bronchovascular sheaths indicative of pulmonary interstistial emphysema, possibly caused by repeated prior exacerbations of asthma. His lung function tests and symptoms improved within months of being treated for his airways disease but the CT findings were unchanged after 2 years.

mDia2 induces the actin scaffold for the contractile ring and stabilizes its position during cytokinesis in NIH 3T3 cells

mDia proteins are mammalian homologues of Drosophila diaphanous and belong to the formin family proteins that catalyze actin nucleation and polymerization. Although formin family proteins of nonmammalian species such as Drosophila diaphanous are essential in cytokinesis, whether and how mDia proteins function in cytokinesis remain unknown. Here we depleted each of the three mDia isoforms in NIH 3T3 cells by RNA interference and examined this issue. Depletion of mDia2 selectively increased the number of binucleate cells, which was corrected by coexpression of RNAi-resistant full-length mDia2. mDia2 accumulates in the cleavage furrow during anaphase to telophase, and concentrates in the midbody at the end of cytokinesis. Depletion of mDia2 induced contraction at aberrant sites of dividing cells, where contractile ring components such as RhoA, myosin, anillin, and phosphorylated ERM accumulated. Treatment with blebbistatin suppressed abnormal contraction, corrected localization of the above components, and revealed that the amount of F-actin at the equatorial region during anaphase/telophase was significantly decreased with mDia2 RNAi. These results demonstrate that mDia2 is essential in mammalian cell cytokinesis and that mDia2-induced F-actin forms a scaffold for the contractile ring and maintains its position in the middle of a dividing cell.

Effect of MDR1 C3435T polymorphism on cure rates of Helicobacter pylori infection by triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP 2C19 genotypes and 23S rRNA genotypes of H. pylori

BACKGROUND

Polymorphism in MDR1 is associated with variation in the plasma level of a proton pump inhibitor.

AIM

To investigate whether MDR1 polymorphism is associated with eradication rates of Helicobacter pylori by a triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP2C19 genotype status and bacterial susceptibility to clarithromycin.

METHODS

A total of 313 patients infected with H. pylori completed the treatment with lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week. MDR1 C3435T polymorphism and CYP2C19 genotypes of patients and sensitivity of H. pylori to clarithromycin were determined.

RESULTS

Logistic regression analysis revealed that the MDR1 polymorphism as well as CYP2C19 genotypes of patients and clarithromycin-resistance of H. pylori were significantly associated with successful eradication. Eradication rates for H. pylori were 82% (83/101: 95% CI = 73-89), 81% (112/139: CI = 73-87), and 67% (44/73: CI = 48-72) in patients with the MDR1 3435 C/C, C/T and T/T genotype, respectively (P = 0.001).

CONCLUSIONS

Polymorphism of MDR1 is one of the determinants of successful eradication of H. pylori by the triple therapy with lansoprazole, amoxicillin and clarithromycin, together with CYP2C19 genotype and bacterial susceptibility to clarithromycin.

Effect of MDR1 C3435T polymorphism on cure rates of Helicobacter pylori infection by triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP 2C19 genotypes and 23S rRNA genotypes of H. pylori

BACKGROUND

Polymorphism in MDR1 is associated with variation in the plasma level of a proton pump inhibitor.

AIM

To investigate whether MDR1 polymorphism is associated with eradication rates of Helicobacter pylori by a triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP2C19 genotype status and bacterial susceptibility to clarithromycin.

METHODS

A total of 313 patients infected with H. pylori completed the treatment with lansoprazole 30 mg b.d., clarithromycin 200 mg b.d. and amoxicillin 750 mg b.d. for 1 week. MDR1 C3435T polymorphism and CYP2C19 genotypes of patients and sensitivity of H. pylori to clarithromycin were determined.

RESULTS

Logistic regression analysis revealed that the MDR1 polymorphism as well as CYP2C19 genotypes of patients and clarithromycin-resistance of H. pylori were significantly associated with successful eradication. Eradication rates for H. pylori were 82% (83/101: 95% CI = 73-89), 81% (112/139: CI = 73-87), and 67% (44/73: CI = 48-72) in patients with the MDR1 3435 C/C, C/T and T/T genotype, respectively (P = 0.001).

CONCLUSIONS

Polymorphism of MDR1 is one of the determinants of successful eradication of H. pylori by the triple therapy with lansoprazole, amoxicillin and clarithromycin, together with CYP2C19 genotype and bacterial susceptibility to clarithromycin.

Pharmacogenomics-based tailored versus standard therapeutic regimen for eradication of H. pylori

Helicobacter pylori eradication rates by triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin at standard doses depend on bacterial susceptibility to clarithromycin and patient CYP2C19 genotypes. We examined the usefulness of a personalized therapy for H. pylori infection based on these factors as determined by genetic testing. First, optimal lansoprazole dosing schedules that would achieve sufficient acid inhibition to allow H. pylori eradication therapy in each of different CYP2C19 genotype groups were determined by a 24-h intragastric pH monitoring. Next, 300 H. pylori-positive patients were randomly assigned to the standard regimen group (lansoprazole 30 mg twice daily (b.i.d.)), clarithromycin 400 mg b.i.d., and amoxicillin 750 mg b.i.d. for 1 week) or the tailored regimen group based on CYP2C19 status and bacterial susceptibility to clarithromycin assessed by genetic testing. Patients with failure of eradication underwent the second-line regimen. The per-patient cost required for successful eradication was calculated for each of the groups. In the first-line therapy, the intention-to-treat eradication rate in the tailored regimen group was 96.0% (95% CI=91.5-98.2%, 144/150), significantly higher than that in the standard regimen group (70.0%: 95% CI=62.2-77.2%, 105/150) (P<0.001). Final costs per successful eradication in the tailored and standard regimen groups were $669 and $657, respectively. In conclusion, the pharmacogenomics-based tailored treatment for H. pylori infection allowed a higher eradication rate by the initial treatment without an increase of the final per-patient cost for successful eradication. However, the precise cost-effectiveness of this strategy remains to be determined.

Changes in HRCT findings in patients with respiratory bronchiolitis-associated interstitial lung disease after smoking cessation

High-resolution computed tomography (HRCT) findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are varied and nonspecific. There is no known report of changes in HRCT findings and respiratory function test results for RB-ILD patients following the cessation of smoking. Five patients with RB-ILD, confirmed by surgical lung biopsy, were retrospectively studied. Each stopped cigarette smoking and did not receive corticosteroid therapy after diagnosis. The clinical symptoms, respiratory function test results and HRCT findings obtained at the final observation were compared with those from the time of diagnosis. Ground-glass opacity and centrilobular nodules corresponding to pathological respiratory bronchiolitis, as well as intralobular fine linear-reticular opacity corresponding to fibrosis involving the subpleural alveolar septa, showed computed tomography-pathological correlations. Both clinical symptoms and the diffusing capacity of the lungs for carbon monoxide improved significantly following smoking cessation, as did ground-glass opacity and centrilobular nodules seen during the initial HRCT examination. Centrilobular nodules and ground-glass opacity, which are the main features of high-resolution computed tomography of respiratory bronchiolitis-associated interstitial lung disease patients and represent pathological respiratory bronchiolitis, can be improved by smoking cessation. The diffusing capacity of the lung for carbon monoxide in respiratory function tests can be also improved.

The Rho-mDia1 pathway regulates cell polarity and focal adhesion turnover in migrating cells through mobilizing Apc and c-Src

Directed cell migration requires cell polarization and adhesion turnover, in which the actin cytoskeleton and microtubules work critically. The Rho GTPases induce specific types of actin cytoskeleton and regulate microtubule dynamics. In migrating cells, Cdc42 regulates cell polarity and Rac works in membrane protrusion. However, the role of Rho in migration is little known. Rho acts on two major effectors, ROCK and mDia1, among which mDia1 produces straight actin filaments and aligns microtubules. Here we depleted mDia1 by RNA interference and found that mDia1 depletion impaired directed migration of rat C6 glioma cells by inhibiting both cell polarization and adhesion turnover. Apc and active Cdc42, which work together for cell polarization, localized in the front of migrating cells, while active c-Src, which regulates adhesion turnover, localized in focal adhesions. mDia1 depletion impaired localization of these molecules at their respective sites. Conversely, expression of active mDia1 facilitated microtubule-dependent accumulation of Apc and active Cdc42 in the polar ends of the cells and actin-dependent recruitment of c-Src in adhesions. Thus, the Rho-mDia1 pathway regulates polarization and adhesion turnover by aligning microtubules and actin filaments and delivering Apc/Cdc42 and c-Src to their respective sites of action.

GAP1 family members constitute bifunctional Ras and Rap GTPase-activating proteins

GAP1(IP4BP) is a member of the GAP1 family of Ras GTPase-activating proteins (Ras GAPs) that includes GAP1(m), CAPRI, and RASAL. Composed of a central Ras GAP domain, surrounded by amino-terminal C(2) domains and a carboxyl-terminal pleckstrin homology/Bruton's tyrosine kinase domain, GAP1(IP4BP) has previously been shown to possess an unexpected GAP activity on the Ras-related protein Rap, besides the predicted Ras GAP activity (Cullen, P. J., Hsuan, J. J., Truong, O., Letcher, A. J., Jackson, T. R., Dawson, A. P., and Irvine, R. F. (1995) Nature 376, 527-530). Here we have shown that GAP1(IP4BP) is indeed an efficient Ras/Rap GAP, having K(m)s of 213 and 42 microm and estimated k(cat)s of 48 and 16 s(-1) for Ras and Rap, respectively. For this dual activity, regions outside the Ras GAP domain are required, as the isolated domain (residues 291-569) retains a pronounced Ras GAP activity yet has very low activity toward Rap. Interestingly, mutagenesis of the Ras GAP arginine finger, and surrounding residues important in Ras binding, inhibit both Ras and Rap GAP activity of GAP1(IP4BP). Although the precise details by which GAP1(IP4BP) can function as a Rap GAP remain to be determined, these data are consistent with Rap associating with GAP1(IP4BP) through the Ras-binding site within the Ras GAP domain. Finally, we have established that such dual Ras/Rap GAP activity is not restricted to GAP1(IP4BP). Although GAP1(m) appears to constitute a specific Ras GAP, CAPRI and RASAL display dual activity. For CAPRI, its Rap GAP activity is modulated upon its Ca(2+)-induced association with the plasma membrane.

Poor metabolizer genotype status of CYP2C19 is a risk factor for developing gastric cancer in Japanese patients with Helicobacter pylori infection

BACKGROUND

Cytochrome P450 2C19 (CYP2C19) polymorphism has been associated with the development of lung, liver or oesophageal cancer by detoxification of carcinogen(s) or activation of procarcinogen(s).

AIM

To clarify the association between CYP2C19 polymorphisms and gastric cancer development in Japanese. Methods : We determined CYP2C19 genotypes (CYP2C19*1, *2 and *3) in 111 Helicobacter pylori-positive patients with gastric cancer and 315 H. pylori-positive controls without gastric cancer consisting of patients with gastritis only or peptic ulcer. Frequencies of CYP2C19 genotypes and serum pepsinogen I and II levels, a biomarker of gastric atrophy, in the gastric cancers and controls were compared.

RESULTS

Frequencies of homozygous extensive metabolizers, heterozygous extensive metabolizers and poor metabolizers were 31.5%, 42.3% and 26.2% in the gastric cancers and 38.1%, 47.0% and 14.9% in the controls, respectively (P = 0.046). Poor metabolizers were associated with an increased risk for developing gastric cancer with the age- and sex-adjusted odds ratio (OR) of 1.975 [95% confidence interval (CI): 1.068-3.649], especially for diffuse type (OR: 3.385, CI: 1.187-9.648). There is no significant association between CYP2C19 genotypes and serum pepsinogen I level or pepsinogen I/II ratios, although serum pepsinogen I level in gastric cancers were significantly decreased.

CONCLUSIONS

In H. pylori-positive Japanese, poor metabolizers of CYP2C19 appear to be at an increased risk for developing gastric cancer, especially diffuse type, and may require an intensive follow-up for scrutinizing possible gastric cancer development.

The disposition of oral amodiaquine in Papua New Guinean children with falciparum malaria

AIMS

We assessed the disposition of oral amodiaquine (AQ) and CYP2C8 polymorphism in 20 children with falciparum malaria.

METHODS

AQ and DEAQ concentrations were determined with SPE-HPLC method. CYP2C8 genotypes were assessed by PCR-RFLP method.

RESULTS

AQ was not detectable beyond day 3 postdose. Cmax for DEAQ was reached in 3.0 days. The mean values for t1/2, MRT, and AUCtotal were 10.1 days, 15.5 days and 4512.6 microg l(-1) day, respectively. All the children were CYP2C8* homozygous.

CONCLUSION

Our data are consistent with those previously reported, and the AQ regimen seems pharmacokinetically adequate in the absence of CYP2C8 polymorphism.

Structural and mechanistic insights into the interaction between Rho and mammalian Dia

Formins are involved in a variety of cellular processes that require the remodelling of the cytoskeleton. They contain formin homology domains FH1 and FH2, which initiate actin assembly. The Diaphanous-related formins form a subgroup that is characterized by an amino-terminal Rho GTPase-binding domain (GBD) and an FH3 domain, which bind somehow to the carboxy-terminal Diaphanous autoregulatory domain (DAD) to keep the protein in an inactive conformation. Upon binding of activated Rho proteins, the DAD is released and the ability of the formin to nucleate and elongate unbranched actin filaments is induced. Here we present the crystal structure of RhoC in complex with the regulatory N terminus of mammalian Diaphanous 1 (mDia1) containing the GBD/FH3 region, an all-helical structure with armadillo repeats. Rho uses its 'switch' regions for interacting with two subdomains of GBD/FH3. We show that the FH3 domain of mDia1 forms a stable dimer and we also identify the DAD-binding site. Although binding of Rho and DAD on the N-terminal fragment of mDia1 are mutually exclusive, their binding sites are only partially overlapping. On the basis of our results, we propose a structural model for the regulation of mDia1 by Rho and DAD.

ROCK-I regulates closure of the eyelids and ventral body wall by inducing assembly of actomyosin bundles

Rho-associated kinase (ROCK) I mediates signaling from Rho to the actin cytoskeleton. To investigate the in vivo functions of ROCK-I, we generated ROCK-I–deficient mice. Loss of ROCK-I resulted in failure of eyelid closure and closure of the ventral body wall, which gave rise to the eyes open at birth and omphalocele phenotypes in neonates. Most ROCK-I^−/− mice died soon after birth as a result of cannibalization of the omphalocele by the mother. Actin cables that encircle the eye in the epithelial cells of the eyelid were disorganized and accumulation of filamentous actin at the umbilical ring was impaired, with loss of phosphorylation of the myosin regulatory light chain (MLC) at both sites, in ROCK-I^−/− embryos. Stress fiber formation and MLC phosphorylation induced by EGF were also attenuated in primary keratinocytes from ROCK-I^−/− mice. These results suggest that ROCK-I regulates closure of the eyelids and ventral body wall through organization of actomyosin bundles.

Cdc42 and mDia3 regulate microtubule attachment to kinetochores

During mitosis, the mitotic spindle, a bipolar structure composed of microtubules (MTs) and associated motor proteins, segregates sister chromatids to daughter cells. Initially some MTs emanating from one centrosome attach to the kinetochore at the centromere of one of the duplicated chromosomes. This attachment allows rapid poleward movement of the bound chromosome. Subsequent attachment of the sister kinetochore to MTs growing from the other centrosome results in the bi-orientation of the chromosome, in which interactions between kinetochores and the plus ends of MTs are formed and stabilized. These processes ensure alignment of chromosomes during metaphase and their correct segregation during anaphase. Although many proteins constituting the kinetochore have been identified and extensively studied, the signalling responsible for MT capture and stabilization is unclear. Small GTPases of the Rho family regulate cell morphogenesis by organizing the actin cytoskeleton and regulating MT alignment and stabilization. We now show that one member of this family, Cdc42, and its effector, mDia3, regulate MT attachment to kinetochores.

Transformation of the monocotyledonous Alstroemeria by Agrobacterium tumefaciens

An efficient procedure is described for the transformation of the monocotyledonous Alstroemeria by Agrobacterium tumefaciens via callus regeneration. Calli derived from ovules were co-cultivated with A. tumefaciens strains EHA101 and LBA4404, which harbored the binary vector plasmids pIG121Hm and pTOK233, respectively. These plasmids contain the beta-glucuronidase gene ( gusA) as a reporter gene and the hygromycin phosphotransferase and neomycin phosphotransferase II ( nptII) genes as selective markers. Inoculated calli were first plated for 4 weeks on medium containing cefotaxime to eliminate bacteria, following which time transformed cells were selected on medium that contained 20 mg/l hygromycin. A histochemical assay for GUS activity revealed that hygromycin-based selection was completed after 8 weeks. The integration of the T-DNA of pIG121Hm and pTOK233 into the genome of the cells was confirmed by PCR analysis. Efficient shoot regeneration from the transformed calli was observed on half-strength MS medium supplemented with 0.5 mg/l naphthaleneacetic acid and 0.5 mg/l benzyladenine after about 5 months of culture. The presence of the gusA and nptII genes in the genomic DNA of regenerated plants was detected by means of PCR and PCR-Southern hybridization, and the expression of these transgenes was verified by reverse transcription-PCR.

An in vitro interethnic comparison of monoamine oxidase activities between Japanese and Caucasian livers using rizatriptan, a serotonin receptor 1B/1D agonist, as a model drug

AIMS

Monoamine oxidase (MAO) is located in human liver, and catalyses the oxidative deamination step of many xenobiotics. However, whether there exists an interethnic difference in MAO activities has, to our knowledge, not been clarified. We aimed to assess the MAO type A (MAO-A) involvement in the metabolic pathway of rizatriptan (RIZ), an antimigraine 5-hydroxytryptamine (5-HT)1B/1D agonist, and the interethnic difference in MAO activities between Caucasians and Japanese using RIZ as a model drug in in vitro experiments.

METHODS

Oxidative deaminase activities were determined with the subcellular fractions of Japanese livers and the microsomal fraction of Caucasian livers using RIZ, 5-HT (MAO-A substrate) and 2-phenylethylamine (PEA) (MAO-B substrate) as substrates.

RESULTS

The oxidative deaminase activities of RIZ vs. 5-HT were highly (r = 0.87 and 0.96, P < 0.001) correlated with each other in both the microsomal and mitochondrial fractions of Japanese livers. Subsequent results were obtained from in vitro experiments using liver microsomes based upon these findings. The oxidative deaminase activities of RIZ were inhibited completely by the nanomolar-order concentration of clorgyline and Ro 41-1049 (MAO-A selective inhibitors), but not by that of Ro 16-6491 (MAO-B selective inhibitor). The majority of the mean Michaelis-Menten values for three substrates toward MAO obtained from six Japanese and six Caucasian liver microsomes reached no significant differences between the two ethnic groups. The mean microsomal oxidative deaminase activities assessed in 18 Japanese and 20 Caucasian livers using the three substrates also showed no significant differences between the two ethnic groups.

CONCLUSIONS

RIZ is mainly metabolized by MAO-A and the in vitro oxidative deaminase activities mediated via MAO-A and -B do not appear to differ between Japanese and Caucasians.

Orthodontic treatment of a case of Becker muscular dystrophy

Becker muscular dystrophy, similar to Duchenne muscular dystrophy, is a X-chromosomal linked anomaly characterized by progressive muscle wasting and weakness. Duchenne-type is known to have severe openbite with a steep mandibular plane, but there are no studies that describe the occlusal and skeletal patterns of the Becker-type. Here, we report the orthodontic treatment of a Becker muscular dystrophy patient. In the correction of his severe skeletal open bite general anesthesia or orthognathic surgery was not an option. Multiloop edgewise archwires were employed for orthodontic treatment. After 3 years and 8 months the open bite was corrected. During the retention period contact between the anterior teeth was maintained 8 months after active treatment despite a marked relapse tendency.

Targeted disruption of the mouse rho-associated kinase 2 gene results in intrauterine growth retardation and fetal death

Rho-associated kinase (ROCK), including the ROCK-I and ROCK-II isoforms, is a protein kinase involved in signaling from Rho to actin cytoskeleton. However, in vivo functions of each ROCK isoform remain largely unknown. We generated mice deficient in ROCK-II by gene targeting. ROCK-II(-/-) embryos were found at the expected Mendelian frequency until 13.5 days postcoitum, but approximately 90% died thereafter in utero. ROCK-II(-/-) mice of both genders that survived were born runts, subsequently developed without gross abnormality, and were fertile. Whole-mount staining for a knocked-in lacZ reporter gene revealed that ROCK-II was highly expressed in the labyrinth layer of the placenta. Disruption of architecture and extensive thrombus formation were found in the labyrinth layer of ROCK-II(-/-) mice. While no obvious alteration in actin filament structures was found in the labyrinth layer of ROCK-II(-/-) placenta and stress fibers were formed in cultured ROCK-II(-/-) trophoblasts, elevated expression of plasminogen activator inhibitor 1 was found in ROCK-II(-/-) placenta. These results suggest that ROCK-II is essential in inhibiting blood coagulation and maintaining blood flow in the endothelium-free labyrinth layer and that loss of ROCK-II leads to thrombus formation, placental dysfunction, intrauterine growth retardation, and fetal death.

Therapeutic impact of CYP2C19 pharmacogenetics on proton pump inhibitor-based eradication therapy for Helicobacter pylori

Current regimens for the eradication of Helicobacter pylori consist of a proton pump inhibitor (PPI) plus one or two antibacterial agents, such as amoxicillin (AMPC), clarithromycin (CAM) or metronidazole (MNZ). PPIs are mainly metabolized by S-mephenytoin 4'-hydroxylase (CYP2C19) in the liver. The polymorphism of CYP2C19 is associated with the pharmacokinetics and pharmacodynamics of PPIs. Eradication rates by PPI-based therapies are also affected by this genotype, as well as bacterial resistance to antibiotics. An individualized treatment strategy based on CYP2C19-related pharmacogenetics or pharmacogenomics and bacterial resistance is expected to increase the cure rate of the initial treatment. It is also necessary to recognize that there is a possible drug-drug interaction between some of the drugs used in this treatment regimen.

[Rho-mediated signal transduction and its physiological roles]

Rho is a member of the Ras-related family of small molecular weight GTP-binding proteins, and Rho works as a molecular switch by shuttling between the GDP-bound inactive form and the GTP-bound active form. Rho is involved in cell motility, cell adhesion, and cytokinesis through the reorganization of the actin cytoskeleton. In addition to this, Rho also regulates Ras-induced transformation, transcriptional activation and cell cycle progression. These actions through the Rho signaling are mediated by downstream Rho effectors. Several putative Rho effectors including ROCK and mDia have been isolated on the basis of their selective binding to the GTP-bound form of Rho. Among them, the ROCK family of Rho-associated serine/threonine protein kinases inactivates myosin phosphatase and actin depolymerizing factor (cofilin/Destrin) to induce stabilization of filamentous actin and increase in the actomyosin-based contractility. mDia binds profilin likely to promote actin polymerization. Thus, these effectors are supposed to work in organization of the actin cytoskeleton. Furthermore, analyses using a ROCK specific inhibitor Y-27632 have suggested that the Rho-ROCK pathway works in contractions of vascular smooth muscles and is involved in malignant cell transformation and tumor invasion and metastasis.

ROCK and mDia1 antagonize in Rho-dependent Rac activation in Swiss 3T3 fibroblasts

The small GTPase Rho acts on two effectors, ROCK and mDia1, and induces stress fibers and focal adhesions. However, how ROCK and mDia1 individually regulate signals and dynamics of these structures remains unknown. We stimulated serum-starved Swiss 3T3 fibroblasts with LPA and compared the effects of C3 exoenzyme, a Rho inhibitor, with those of Y-27632, a ROCK inhibitor. Y-27632 treatment suppressed LPA-induced formation of stress fibers and focal adhesions as did C3 exoenzyme but induced membrane ruffles and focal complexes, which were absent in the C3 exoenzyme-treated cells. This phenotype was suppressed by expression of N17Rac. Consistently, the amount of GTP-Rac increased significantly by Y-27632 in LPA-stimulated cells. Biochemically, Y-27632 suppressed tyrosine phosphorylation of paxillin and focal adhesion kinase and not that of Cas. Inhibition of Cas phosphorylation with PP1 or expression of a dominant negative Cas mutant inhibited Y-27632-induced membrane ruffle formation. Moreover, Crk-II mutants lacking in binding to either phosphorylated Cas or DOCK180 suppressed the Y-27632-induced membrane ruffle formation. Finally, expression of a dominant negative mDia1 mutant also inhibited the membrane ruffle formation by Y-27632. Thus, these results have revealed the Rho-dependent Rac activation signaling that is mediated by mDia1 through Cas phosphorylation and antagonized by the action of ROCK.

Comparison of lansoprazole and famotidine for gastric acid inhibition during the daytime and night-time in different CYP2C19 genotype groups

BACKGROUND

The acid inhibitory effect of lansoprazole depends on the S-mephenytoin 4'-hydroxylase (CYP2C19) genotype status. The effect of famotidine is independent of this genotype.

AIM

To investigate the acid inhibitory effects of lansoprazole vs. famotidine during the daytime and night-time with reference to different CYP2C19 genotypes.

METHODS

Fifteen healthy volunteers were given 20 mg famotidine twice a day or 30 mg lansoprazole once a day for 8 days. On post-dose day 8, 24-h intragastric pH monitoring was performed.

RESULTS

During the daytime, the intragastric pH with lansoprazole was significantly higher than that with famotidine in the heterozygous extensive metabolizer group, whereas no significant difference was observed in the homozygous extensive metabolizer group. During the night-time, the intragastric pH with famotidine was quite similar to that with lansoprazole in the heterozygous extensive metabolizer and poor metabolizer groups. However, during the night-time, the intragastric pH with famotidine was significantly higher than that with lansoprazole in the homozygous extensive metabolizer group.

CONCLUSIONS

An insufficient acid inhibition by lansoprazole during the night-time in the homozygous extensive metabolizer group could be compensated for by famotidine. CYP2C19 genotype testing appears to be useful for predicting the optimal acid inhibitory drug treatment collated with circadian intragastric pH change.

Effects of CYP2C19 genotypic differences in the metabolism of omeprazole and rabeprazole on intragastric pH

BACKGROUND

Omeprazole is mainly metabolized in the liver by CYP2C19, a genetically determined enzyme, whereas rabeprazole is mainly reduced non-enzymatically and partially metabolized by CYP2C19. The therapeutic effects of rabeprazole are therefore assumed to be less affected by an individual's CYP2C19 status.

AIM

To investigate the acid inhibitory effects and plasma levels of omeprazole and rabeprazole with reference to different CYP2C19 genotypes.

METHODS

Fifteen healthy volunteers took a daily dose of 20 mg of omeprazole or rabeprazole for 8 days. On post-dose days 1 and 8, 24-h profiles of intragastric pH were recorded and plasma concentrations of omeprazole, rabeprazole and their metabolites were determined.

RESULTS

After single and repeated doses of omeprazole, the intragastric pH values and plasma concentrations of omeprazole and its metabolites were significantly dependent on the CYP2C19 genotype. Significant differences in the same kinetic and dynamic parameters were also observed after single doses of rabeprazole. Although the plasma levels of rabeprazole differed among the different CYP2C19 genotype groups after repeated doses, no significant differences in intragastric pH values were observed.

CONCLUSIONS

The acid inhibitory effects of omeprazole and rabeprazole are significantly dependent on the CYP2C19 genotype status, as well as on their intrinsic pharmacokinetic and pharmacodynamic characteristics and dosing schemes.

Effect of high-dose lansoprazole on intragastic pH in subjects who are homozygous extensive metabolizers of cytochrome P4502C19

BACKGROUNDS AND AIM

Lansoprazole is mainly metabolized by cytochrome P4502C19 (CYP2C19) in the liver. The effect of lansoprazole is assumed to be insufficient in subjects who are homozygous extensive metabolizers of CYP2C19. This study aimed to examine whether the CYP2C19 genotype status affected the acid-inhibitory effects of lansoprazole and to develop a strategy to overcome this pharmacogenetic problem.

METHODS

Eighteen Helicobacter pylori-negative healthy volunteers, whose CYP2C19 genotypic status had been assessed, participated in the study. They consisted of 7 subjects who were homozygous extensive metabolizers, 7 subjects who were heterozygous extensive metabolizers, and 4 subjects who were poor metabolizers of CYP2C19, who took a placebo or lansoprazole 30 mg once daily in the morning for 8 days. On day 8 of dosing, 24-hour intragastric pH values were recorded. Five of the homozygous extensive metabolizer subjects underwent the 24-hour intragastric pH monitoring on day 8 of dosing of lansoprazole 30 mg 4 times daily.

RESULTS

When lansoprazole 30 mg was given once daily, the mean 24-hour intragastric pH values in the subjects who were homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers were 4.5, 4.9, and 5.5, respectively (P <.005). On day 8 of dosing of lansoprazole 30 mg 4 times daily in subjects who were homozygous extensive metabolizers, the mean 24-hour intragastric pH value was 7.4.

CONCLUSION

The effect of lansoprazole on intragastric pH depended significantly on CYP2C19 genotype status. Complete acid inhibition could be achieved by the frequent administration of lansoprazole (eg, 30 mg 4 times daily) in subjects who were homozygous extensive metabolizers. A genotyping test of CYP2C19 status appears useful for prescribing an optimal dosing scheme of lansoprazole.

[The relationship between fall-related activity restriction and functional fitness in elderly women]

The purpose of this study was to assess the relationship between experiences of falls or fear of falling and functional fitness in the elderly. A total of 41 women, aged 66-88, who visited Fall Prevention Clinic in Tokyo Metropolitan Geriatric Hospital, underwent an interview and functional assessment. We used a questionnaire about falls, fear of falling, activity restriction, and twelve variables were used to assess functional fitness. Data were collected from June 2000 to November 2001. The subjects were classified into four subgroups: the faller group (n = 29) were subjects who had at least one or more experiences of falling accidents in the past one year; the non-faller group (n = 12) were subjects who did not have any falling accidents in the past one year; the activity restricted group (n = 12) were subjects who were restricted from going out because of fear of falling; the activity non-restricted group (n = 23) consisted of subjects who did not have any restriction concerning going out because of fear of falling. The results were: 1) Among all subjects, 85.4% had fear of falling. Among the subjects who had fear of falling. 34.3% had restricted outdoor activities due to the fear of falling. 2) Where 86.2% of the faller group responded that they had fear of falling. 83.3% of the non-faller group also responded as having fear of falling. Of the faller group, 44.0% had some restriction concerning going out because of fear of falling. In the non-faller group, 10.0% of them showed some restriction concerning going out because of fear of falling. The rate of activity restriction in the faller group was significantly higher (p < 0.05) than in the non-faller group. 3) The faller group had significantly reduced LNG with eyes open and closed, one-leg balance with eyes open, tandem walking, grip strength, and leg extension than the non-faller group. 4) The activity-restricted group exhibited significantly reduced one-leg balance with eyes open, Up & Go test, grip strength, and leg extension than the activity non-restricted group. In conclusion, lower leg strength and walking ability as well as history of falls are significant predictors of activity restriction in elderly women related to fear of falling.

[A case of lymphocytic interstitial pneumonia with Sjögren's syndrome and systemic lupus erythematosus in which human herpes virus-6 infection was the suspected pathogen]

A 47-year-old-woman was admitted to our hospital complaining of thirst and dry cough after catching cold. Sjögren's syndrome (SjS) and systemic lupus erythematosus (SLE) were diagnosed. Chest X-P and CT findings suggested strongly that she had interstitial pneumonia. Thoracoscopic lung biopsy was therefore performed, and the biopsy specimens showed marked infiltration of small lymphocytes and of plasma cells into the alveolar walls and interlobular septa. Since the infiltrating cells were not atypical and gene analysis did not show mono-clonality, we made a diagnosis of lymphocytic interstitial pneumonia (LIP). Because the patient's symptoms appeared only after she caught cold, we suspected that virus infections were somewhat involved in the etiology of these diseases. The level of human herpesvirus-6 (HHV-6) antibody was high, and furthermore, HHV-6 was detected using the polymerase chain reaction from lung biopsy specimens. We suspected in this case that LIP, SjS, and SLE had appeared concomitantly after an active HHV-6 infection.

[The effect of O2 therapy on mixed venous concentration of endothelin-1 in chronic obstructive pulmonary disease]

Pulmonary hypertension (PH) is an important factor in the prognosis of cases of chronic obstructive pulmonary disease (COPD), and endothelin-1 (ET-1) is a major factor in the development of PH in COPD. Oxygen (O2) therapy improves the prognosis of COPD by suppressing the development of PH. We therefore assessed the correlation of PH and ET-1, and the effect of O2 therapy on the plasma ET-1 concentration. In COPD patients, the plasma ET-1 level in mixed venous blood, but not in arterial blood, was negatively correlated with mixed venous O2 tension and positively correlated with pulmonary vascular resistance. No such correlation, however, was observed in the case of plasma HANP or plasma BNP. O2 administration significantly suppressed the plasma ET-1 level. This level in mixed venous blood was thought to serve as a marker of PH in COPD. and O2 administration decreased the plasma ET-1 level in mixed venous blood. It consequently attenuated PH.

Effects of CYP3A4 inhibition by diltiazem on pharmacokinetics and dynamics of diazepam in relation to CYP2C19 genotype status

Diazepam is metabolized by CYP2C19 and CYP3A4 in the liver. CYP2C19 shows genetic polymorphism associated with the poor metabolizer (PM) and extensive metabolizer (EM) phenotypes. The aim of this study was to assess the effect of diltiazem, a CYP3A4 inhibitor, on pharmacokinetics and dynamics of diazepam in relation to CYP2C19 genotype status. Thirteen healthy volunteers (eight EMs and five PMs) were given placebo or diltiazem (200 mg) orally for 3 days before and for 7 days after the oral 2-mg dose of diazepam in a double-blind, randomized, crossover manner. The pharmacokinetics and pharmacodynamics of diazepam were assessed with and without diltiazem. Plasma concentrations and area under the plasma concentration-time curves (AUCs) of diazepam and N-desmethyldiazepam were significantly greater in the PM compared with the EM group during the placebo phase. Diltiazem significantly increased AUC and prolonged elimination t(1/2) of diazepam in both the PM and EM groups. These pharmacokinetic changes, however, caused no significant difference in the pharmacodynamics between the two trial phases. Diltiazem affects the pharmacokinetics of diazepam in the PM and EM groups of CYP2C19. Inhibition of CYP3A4 by a concomitant substrate drug like diltiazem may cause a pharmacokinetic interaction with diazepam irrespective of CYP2C19 genotype status, but whether this interaction would reflect a pharmacodynamic change of diazepam remains unconfirmed by our study.

Rho-dependent transfer of Citron-kinase to the cleavage furrow of dividing cells

Citron-kinase (Citron-K) is a Rho effector working in cytokinesis. It is enriched in cleavage furrow, but how Rho mobilizes Citron-K remains unknown. Using anti-Citron antibody and a Citron-K Green Fluorescence Protein (GFP)-fusion, we monitored its localization in cell cycle. We have found: (1) Citron-K is present as aggregates in interphase cells, disperses throughout the cytoplasm in prometaphase, translocates to cell cortex in anaphase and accumulates in cleavage furrow in telophase; (2) Rho colocalizes with Citron-K in the cortex of ana- to telophase cells and the two proteins are concentrated in the cleavage furrow and to the midbody; (3) inactivation of Rho by C3 exoenzyme does not affect the dispersion of Citron-K in prometaphase, but prevented its transfer to the cell cortex, and Citron-K stays in association with the midzone spindles of C3 exoenzyme-treated cells. To clarify further the mechanism of the Rho-mediated transfer and concentration of Citron-K in cleavage furrow, we expressed active Val14RhoA in interphase cells expressing GFP-Citron-K. Val14RhoA expression transferred Citron-K to the ventral cortex of interphase cells, where it formed band-like structures in a complex with Rho. This structure was localized at the same plane as actin stress fibers, and they exclude each other. Disruption of F-actin abolished the band and dispersed the Citron-K-Rho-containing patches throughout the cell cortex. Similarly, in dividing cells, a structure composed of Rho and Citron-K in cleavage furrow excludes cortical actin cytoskeleton, and disruption of F-actin disperses Citron-K throughout the cell cortex. These results suggest that Citron-K is a novel type of a passenger protein, which is dispersed to the cytoplasm in prometaphase and associated with midzone spindles by a Rho-independent signal. Rho is then activated, binds to Citron-K and translocates it to cell cortex, where the complex is then concentrated in the cleavage furrow by the action of actin cytoskeleton beneath the equator of dividing cells.

Comparison of the kinetic disposition of and serum gastrin change by lansoprazole versus rabeprazole during an 8-day dosing scheme in relation to CYP2C19 polymorphism

BACKGROUND

Little is known about differences in the disposition kinetics and pharmacological effects on gastrin levels between lansoprazole and rabeprazole given in a repeated dosing scheme with respect to the polymorphic CYP2C19.

AIM

To provide preliminary information that should be considered when prescribing proton-pump inhibitors (PPIs) for the treatment of acid-related diseases with reference to the CYP2C/9 genotypic status.

METHODS

Helicobacter pylori-negative healthy volunteers were divided into the following three groups (n = 5 each) on the basis of genotyping for CYP2C19: homozygous (hmEMs) and heterozygous extensive metabolizers (htEMs), and poor metabolizers (PMs). All received once-daily 30-mg doses of lansoprazole or 10-mg doses of rabeprazole during an 8-day course in a crossover manner.

RESULTS

The relative values for the area under the serum concentration-time curve (AUC) of lansoprazole and rabeprazole in the hmEMs, htEMs, and PMs after the final doses were 1:1.7:3.9 and 1:1.7:3.8, respectively. The relative AUCs of gastrin in the hmEMs, htEMs, and PMs were 1.6:2.6:3.1 for lansoprazole and 1.6:2.6:2.9 for rabeprazole, respectively.

CONCLUSION

The disposition kinetic behavior of the two PPIs is co-segregated with CYP2C19. The magnitude of CYP2C19-dependent drug availability in the systemic circulation and resulting gastrin response appears to be fairly similar between the two drugs within the same CYP2C19 genotypic groups after a multiple-dosing regimen.

[Incidence and prognosis of, and risk factors for the home-bound in a community elderly population]

This longitudinal study examined numbers of homebound and bed bound individuals over time, and risk factors in a rural community elderly populations. A total of 731 older persons who needed no assistance of another person in traveling from their homes participated in the baseline survey in 1992 and were assessed annually for their ability to travel for subsequent six-years. We defined operationally a homebound status as the necessity for assistance of another person to be able to leave home, but without being bedbound. During the follow-up period, 86 homebound (23.7 per 1,000 person-years) and 32 bedbound cases (8.4 per 1,000 person-years) were noted, the former being 2.8 times more likely to occur. Of the newly bound cases 26% returned to a state capable of leaving home by themselves one year later, and maintained this independent living level even two years later. Of the other cases who remained as homebound or bedbound one year later, only one (1/31) had returned to independent living after two years; most of them became bedbound at home, hospital admitted or deceased. Stepwise multiple logistic regression analysis showed that independent risk factors for the homebound include older age, male gender, slower walking speed, history of hospital admission in the previous year, lower masticatory ability, and higher level of serum beta 2-microglobin. These results indicate that health promotion programs for prevention of becoming homebound among community elderly people should target more intensively assistance to maintaining walking and masticatory ability. In addition, public health professionals should pay more attention to elderly people shortly after hospital discharge.

Variant transthyretin in blood circulation can transverse the blood-cerebrospinal barrier: qualitative analyses of transthyretin metabolism in sequential liver transplantation

BACKGROUND

Although the choroid6 plexus of the brain is one of the most important production sites of transthyretin (TTR), the metabolism of TTR secreted in cerebrospinal fluid (CSF) remains to be elucidated.

METHODS

To perform qualitative analysis of variant TTR in CSF of patients who underwent a sequential liver transplantation using an explanted familial amyloidotic polyneuropathy (FAP) ATTR Val30 Met patient's liver, levels and forms of TTR of the two patients were analyzed by means of enzyme linked immunosorbent assay (ELISA) and matrix-assisted laser desorption/time-of-flight mass spectrometer (MALDI/TOF-MS), respectively.

RESULTS

After the operation, variant TTR levels in serum increased, and in CSF, a significant peak of free form of ATTR Val30 Met was detected in the transplanted patients whose CSF had shown no variant TTR before the operation.

CONCLUSIONS

These findings suggest that the variant TTR can cross-the blood-CSF barrier and migrate into CSF from blood circulation. Because leptomeningeal amyloidosis occurs in FAP ATTR Val30 Met as the progression of the disease, this information suggests that in addition to peripheral neuropathy, disorders of the central nervous system (CNS) should be given an attention in patients who underwent sequential liver transplantation using an explanted FAP ATTR Val30 Met patient's liver.

[HRCT findings for four cases of measles pneumonia]

Although, in Western countries, adult-onset pneumonia that is associated with measles is not rare, reports of its incidence in Japan have been sparse. Among eight adolescent and adult (16-34-year-old) measles patients hospitalized in National Sanatorium Tsuruga Hospital, we found four in whom chest radiography and CT revealed pneumonia. The high-resolution lung CTs of these patients revealed features differing from those characteristic of bacterial pneumonia: bronchial wall thickness, centrilobular nodules in ground glass opacity, interstitial lesions (interlobular septal thickening, fissure thickening, pleural effusion) and lymphadenopathy. Of these findings, the centrilobular nodules in ground glass opacity were marked in these cases, and so this may be the most prominent finding in measles pneumonia; and furthermore, since interlobular septal thickening has not been reported in mycoplasma pneumonia or other atypical pneumonias, it may indicate a measles-specific, virus-induced pneumonia.

Focal contacts as mechanosensors: externally applied local mechanical force induces growth of focal contacts by an mDia1-dependent and ROCK-independent mechanism

The transition of cell-matrix adhesions from the initial punctate focal complexes into the mature elongated form, known as focal contacts, requires GTPase Rho activity. In particular, activation of myosin II-driven contractility by a Rho target known as Rho-associated kinase (ROCK) was shown to be essential for focal contact formation. To dissect the mechanism of Rho-dependent induction of focal contacts and to elucidate the role of cell contractility, we applied mechanical force to vinculin-containing dot-like adhesions at the cell edge using a micropipette. Local centripetal pulling led to local assembly and elongation of these structures and to their development into streak-like focal contacts, as revealed by the dynamics of green fluorescent protein-tagged vinculin or paxillin and interference reflection microscopy. Inhibition of Rho activity by C3 transferase suppressed this force-induced focal contact formation. However, constitutively active mutants of another Rho target, the formin homology protein mDia1 (Watanabe, N., T. Kato, A. Fujita, T. Ishizaki, and S. Narumiya. 1999. Nat. Cell Biol. 1:136-143), were sufficient to restore force-induced focal contact formation in C3 transferase-treated cells. Force-induced formation of the focal contacts still occurred in cells subjected to myosin II and ROCK inhibition. Thus, as long as mDia1 is active, external tension force bypasses the requirement for ROCK-mediated myosin II contractility in the induction of focal contacts. Our experiments show that integrin-containing focal complexes behave as individual mechanosensors exhibiting directional assembly in response to local force.

Effects of genotypic differences in CYP2C19 status on cure rates for Helicobacter pylori infection by dual therapy with rabeprazole plus amoxicillin

Rabeprazole is a potent proton pump inhibitor and is mainly reduced to thioether rabeprazole by a non-enzymatic pathway and partially metabolized to demethylated rabeprazole by CYP2C19 in the liver. We intended to determine a cure rate for Helicobacter pylori infection by dual rabeprazole/amoxicillin therapy in relation to CYP2C19 genotype status prospectively. Ninety-seven patients with gastritis and H. pylori infection completed the dual therapy with 10 mg of rabeprazole bid and 500 mg of amoxicillin tid for 2 weeks. At 1 month after treatment, cure of H. pylori infection was assessed on the basis of histology, a rapid urease test, culture, polymerase chain reaction (PCR), and 13C-urea breath test. CYP2C19 genotype status was determined by a PCR-restriction fragment length polymorphism method. Of the 97 patients, 33 were homozygous extensive metabolizers (homEM), 48 were heterozygous extensive metabolizers (hetEM), and 16 were poor metabolizers (PM). Cure of H. pylori infection was achieved in 79 of the 97 patients (81.4%, 95%CI = 71.9-88.7). Significant differences in cure rates among the homEM, hetEM, and PM groups were observed; 60.6% (95%CI = 42.1-77.3), 91.7% (95%CI = 80.0-97.7), and 93.8% (95%CI = 69.8-99.8), respectively (P = 0.0007). Twelve patients without cure after initial treatment (10 homEMs and 2 hetEMs) were successfully retreated with rabeprazole 10 mg q.i.d. and amoxicillin 500 mg q.i.d. for 2 weeks. The cure rates for H. pylori infection by dual rabeprazole/amoxicillin therapy depended on the CYP2C19 genotype status. This dual therapy appears to be effective for hetEM and PM patients. However, high dose dual rabeprazole/amoxicillin therapy was effective even for homEM patients. Therefore, the genotyping test of CYP2C19 appears to be a clinically useful tool for the optimal dual treatment with rabeprazole plus amoxicillin.

Pharmacodynamic effects and kinetic disposition of rabeprazole in relation to CYP2C19 genotypes

BACKGROUND

S-mephenytoin 4'-hydroxylase (CYP2C19) catalyses the metabolism of rabeprazole to some extent. Based on the metabolic and pharmacokinetic differences among other proton pump inhibitors such as omeprazole, lansoprazole and pantoprazole, rabeprazole appears to be the least affected proton pump inhibitor by the CYP2C19-related genetic polymorphism.

AIM

To determine whether the pharmacodynamic effects of rabeprazole on intragastric pH and serum gastrin levels, and its pharmacokinetics depend on the CYP2C19 genotype status.

METHODS

Eighteen healthy subjects, whose CYP2C19 genotype status was previously determined, participated in the study. They consisted of six each of homozygous extensive metabolisers (homo EMs), heterozygous extensive metabolisers (hetero EMs), and poor metabolisers (PMs). Helicobacter pylori status was determined by serology. After a single oral dose of 10 mg or 20 mg rabeprazole or water only (baseline data), intragastric pH values were monitored for 24 h. Plasma levels of rabeprazole and serum gastrin were also measured for 24 h post-dose.

RESULTS

Five homo EM, six hetero EM and four PM subjects were H. pylori-negative. After rabeprazole administration, significant differences in intragastric mean pH values, serum gastrin AUC(0-24) and plasma levels of rabeprazole were observed among the three different genotype groups.

CONCLUSION

The pharmacodynamic effects of rabeprazole and its pharmacokinetics depend on the CYP2C19 genotype status.

[Acute eosinophilic pneumonia with positive response to smoking challenge test, suggesting the involvement of health food]

A 17-year-old girl was admitted to our hospital because of acute febrile illness, progressive dyspnea and severe hypoxemia. Chest radiography and HRCT showed bilateral diffuse ground-glass opacities, consolidation, Kerley lines and pleural effusion. Analysis of bronchoalveolar lavage fluid showed 41.9% eosinophils, and a transbronchial lung biopsy revealed infiltration of eosinophils into the alveolar septa and mild alveolar septal edema. The patient's condition was improved immediately by corticosteroid therapy. She had begun smoking and taking health food (chitosan) 3 months before the admission. A smoking challenge test was positive and a drug-induced lymphocyte stimulation test for chitosan was positive. These findings suggested acute eosinophilic pneumonia caused by smoking and health food. The concentration of interleukin-5 (IL-5) in the serum and BALF/granulocyte colony-stimulating factor (G-CSF) in the serum on admission were very high, but decreased after the improvement. Therefore, it is likely that IL-5 and G-CSF are important in the onset of acute eosinophilic pneumonia.

[Clinical significance of sialyl SSEA-1 (SLX) in patients with idiopathic interstitial pneumonia]

Serum SLX levels were measured in 29 patients with idiopathic interstitial pneumonia (IIP) to evaluate its clinical significance. Serum SLX had positive correlations with the BALF neutrophil ratio but not with the severity or the disease activity in patients with IIP, and bronchoalveolar lavage fluid (BALF) SLX had positive correlations with the BALF neutrophil count. Epithelial lining fluid (ELF) SLX levels showed positive correlations with serum SLX, but were much higher. These results suggest that increases of serum SLX may reflect increases of SLX in the lung tissues. Thus, we speculate that increases of the serum SLX level may represent increases of the BALF neutrophil count. Patients with higher SLX showed poor therapeutic responses and poor prognoses in comparison with those with normal SLX for the reason that serum SLX level represents BALF neutrophil level.

Involvement of human liver cytochrome P4502B6 in the metabolism of propofol

AIMS

To determine the cytochrome P450 (CYP) isoforms involved in the oxidation of propofol by human liver microsomes.

METHODS

The rate constant calculated from the disappearance of propofol in an incubation mixture with human liver microsomes and recombinant human CYP isoforms was used as a measure of the rate of metabolism of propofol. The correlation of these rate constants with rates of metabolism of CYP isoform-selective substrates by liver microsomes, the effect of CYP isoform-selective chemical inhibitors and monoclonal antibodies on propofol metabolism by liver microsomes, and its metabolism by recombinant human CYP isoforms were examined.

RESULTS

The mean rate constant of propofol metabolism by liver microsomes obtained from six individuals was 4.2 (95% confidence intervals 2.7, 5.7) nmol min(-1) mg(-1) protein. The rate constants of propofol by microsomes were significantly correlated with S-mephenytoin N-demethylation, a marker of CYP2B6 (r = 0.93, P < 0.0001), but not with the metabolic activities of other CYP isoform-selective substrates. Of the chemical inhibitors of CYP isoforms tested, orphenadrine, a CYP2B6 inhibitor, reduced the rate constant of propofol by liver microsomes by 38% (P < 0.05), while other CYP isoform-selective inhibitors had no effects. Of the recombinant CYP isoforms screened, CYP2B6 produced the highest rate constant for propofol metabolism (197 nmol min-1 nmol P450-1). An antibody against CYP2B6 inhibited the disappearance of propofol in liver microsomes by 74%. Antibodies raised against other CYP isoforms had no effect on the metabolism of propofol.

CONCLUSIONS

CYP2B6 is predominantly involved in the oxidation of propofol by human liver microsomes.